[Help-glpk] problem with dual

[name name]

Hello,


I have a model like this.

When I try to get a dual I have all value 0.

GLPK.glp_get_col_dual(lp,colId+1) send 0 for all value. 

How can I solve this problem?

Thank you

Onor

P.S. my model is

\* Problem: Unknown *\

Minimize
 objective: + x_1 + x_2 + x_3 + x_4 + x_5

Subject To
 constraint1: + 5 x_1 >= 48
 constraint2: + 2 x_2 >= 35
 constraint3: + 2 x_3 >= 24
 constraint4: + 2 x_4 >= 10
 constraint5: + x_5 >= 8

End